Additive manufacturing using stimuli-responsive high-performance polymers

ABSTRACT

The present invention provides high performance polymer (HPP) compositions, methods, processes, and systems for the manufacture of three-dimensional articles made of polymers using molding or 3D printing. The HPP compositions comprise a first HPP dissolved in a solvent and a second HPP present as a solid having particular particle size.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit U.S. Provisional Application No.62/336,510 filed May 13, 2016, entitled “Toward Room-TemperatureAdditive Manufacturing with High Performance Polymers,” which isincorporated herein by reference in its entirety.

FIELD OF INVENTION

The present invention relates to compositions of high performancepolymers, and methods and apparatus for creating three-dimensionalarticles using the compositions.

BACKGROUND

Three-dimensional (3D) printing refers to processes that create 3Dobjects based upon digital 3D object models and a materials dispenser.In 3D printing, a dispenser moves in at least 2-dimensions and dispensesmaterial according to a determined print pattern. To build a 3D object,a platform that holds the object being printed is adjusted such that thedispenser is able to apply many layers of material, and printing manylayers of material, one layer at a time, may print a 3D object.

A conventionally known 3D printing process is the UV ink-jet process. Itis a three-stage process of applying a material, printing a UV-curableliquid, and finally hardened using a UV source. These steps are repeatedlayer-by-layer. In conventional 3D printing, disclosed in U.S. Pat. Nos.6,375,874 and 6,416,850, generally an inkjet type print head delivers aliquid or a colloidal binder material to layers of a powdered buildmaterial. The printing technique involves applying a layer of a powderedbuild material to a surface typically using a roller. After the buildmaterial is applied to the surface, the print head delivers the liquidbinder to predetermined areas of the layer of material. The binderinfiltrates the material and reacts with the powder, causing the layerto solidify in the printed areas by, for example, activating an adhesivein the powder. The binder also penetrates into the underlying layers,producing interlayer bonding. After the first cross-sectional portion isformed, the previous steps are repeated, building successivecross-sectional portions until the final object is formed.

The oldest and the best-known laser-based 3D printing process isstereolithography (SLA). In this process, a liquid composition of aradiation-curable polymer is hardened layer-by-layer by using a laser. Asimilar process is Selective Laser Sintering (SLS) in which athermoplastic or a sinterable metal is sintered selectivelylayer-by-layer by a laser to form the 3D object.

U.S. Pat. No. 5,121,329 describes the fused deposition modeling (FDM)process for the production of three-dimensional objects using anextrusion-based, digital manufacturing system. There are also otherknown processes that are substantially analogous with slightdifferences, for example fused filament fabrication (FFF), meltextrusion manufacturing (MEM) or selective deposition modeling (SDM).

In the FDM method, two different polymer filaments are melted in anozzle and are printed selectively. One of the materials involves asupport material, which is needed only at locations above which anoverhanging part of the 3D object is printed and requires support duringthe subsequent printing procedure. The support material can be removedsubsequently, e.g. via dissolution in acids, bases or water. The othermaterial (the build material) forms the actual 3D object. Here again,the print is generally achieved layer-by-layer.

SUMMARY

The present invention provides compositions, methods, processes, andsystems for manufacture of three-dimensional articles composed ofpolymers, such as high performance polymers (HPP).

Disclosed are compositions of HPP. The compositions comprise a first HPPdissolved in a solvent, and a second HPP as a solid.

In one aspect, a method for printing a three-dimensional article isprovided. The disclosed method comprises depositing a high-performancepolymer (HPP) composition comprising a first HPP dissolved in a solventand a second HPP as a solid, exposing the HPP composition to a stimulusto form a polymer layer of the three-dimensional article, and repeatingthe steps to manufacture remainder of the three-dimensional article.

In another aspect, disclosed are methods for manufacturing athree-dimensional article, the method comprising depositing the powderof first HPP on a build plate to form a powder bed, printing a solutioncomprising a second HPP dissolved in a solvent at selected locations onthe powder bed, exposing the printed solution to a stimulus to form apolymer layer of the three-dimensional article, and repeating the stepsto manufacture remainder of the three-dimensional article.

In another aspect, a three-dimensional article made by the process ofprinting a high-performance polymer (HPP) composition comprising a firstHPP dissolved in a solvent and a second HPP as a solid, exposing the HPPcomposition to a stimulus to form a polymer layer of thethree-dimensional article, repeating the steps to form a remainder ofthe three-dimensional article, and curing the article for less thanabout 1 minute.

These and other aspects of the present invention will become evidentupon reference to the following detailed description.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A-1D illustrates a method of printing a three-dimensional articlelayer by layer as disclosed herein. In FIG. 1A, the roller 5, deposits ahigh performance polymer (HPP) as a powder from a powder bed reservoir 2to the powder bed 1. The build plate 3 can move in an up and downdirection as needed. The head 4 prints a HPP composition on the powderbed 1. FIG. 1B shows a single layer being patterned. In FIG. 1C, theroller 5, deposits HPP from a powder bed reservoir 2 to the powder bed1. FIG. 1D shows that the HPP has formed a new powder bed layer, and theprocess can be repeated to print a three-dimensional article layer bylayer.

FIG. 2A-2D illustrates the procedure for preparing a rectangular 3Dproduct by molding a paste of powder PEEK and BPA-PEEK solution. FIG. 2Ashows the paste. FIG. 2B shows the paste placed in a rectangular mold.FIG. 2C shows the 3D rectangular product after it was removed from themold. FIG. 2D shows the 3D rectangular product after it was cured.

FIG. 3A-3B illustrates the dynamic mechanical analysis (DMA) ofthree-dimensional product after each soaking and baking cycle. FIG. 3Ashows that the E′ value changes after the first soaking and bakingcycle, but does not change after additional soaking and baking cycle.FIG. 3B shows that the soaking and baking cycles do not change the glasstransition temperature (Tg).

FIG. 4A-4B illustrates 3D products manufactured by syringe printing apowder PEEK and BPA-PEEK solution. FIG. 4A shows a 3D log-like structuremanufactured by syringe printing. FIG. 4B shows the letter “W” createdby syringe printing.

FIG. 5 illustrates dynamic mechanical analysis (DMA) ofthree-dimensional products made using smaller particle size PEEK polymerand one made using larger particle size PEEK polymer.

FIG. 6 illustrates the stress-strain plot of the three-dimensionalproduct.

FIG. 7 illustrates a 3D product manufactured using PEEK powder and boundwith UV activated fenchone solution of epoxy-PEEK and photoinitiator.

DETAILED DESCRIPTION I. Definitions

Unless otherwise stated, the following terms used in this application,including the specification and claims, have the definitions givenbelow. It must be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise.

As used herein, a “build plate” refers to a solid surface made frommaterial such as glass, metal, ceramic, plastic, polymer, and the like.

The term “optional” or “optionally” means that the subsequentlydescribed event or circumstance may or may not occur, and that thedescription includes instances where the event or circumstance occursand instances where it does not.

All publications, patents and patent applications cited herein, whethersupra or infra, are hereby incorporated by reference in their entirety.

II. Overview

Disclosed are methods for additive manufacturing of high performancepolymer (HPPs) that is based upon the use of HPP solutions to bind andfuse insoluble particles of HPPs and methods for manufacturing articlesmade of polymers using three-dimensional printing. The disclosed methodshave the advantage of being able to rapidly print three-dimensionalarticles that have better mechanical properties, better thermalproperties, and the like. The disclosed methods are more flexible thanother art methods in that they allow the three-dimensional article to bebuilt around another, such as a conducting wire to make a circuit. Inaddition, the manufactured articles have molecular structural featuresand physical properties that match those of the final polymers, such asKapton® polymers, polyketone polymers, and polyethersulfone polymers.

In one application, soluble polyether ether ketone (PEEK) polymers canbe prepared and dissolved in organic solvents such as toluene, carvone,THF, spearmint oil, α-terpinene, limonene, α-pinene, fenchone, benzene,and combinations thereof. The solutions can be used to bind insolubleparticles (10-50 micron diameters) of a HPP, such as PEEK, or any otherpolymer. The resulting mixture can form a paste that can be molded orextruded, and then sintered. Molding prior to sintering provided a meansto generate parts from HPPs that were cast from non-reconfigurabledesigns. Material extrusion provided a means to generate 3D objects fromdigitally reconfigurable designs using material extrusion printers. TheHPP solutions can also be formulated to have viscosities ranging from1-50 cP, allowing for ink jet printing. The solutions of HPPs can beprinted by ink jetting into beds of insoluble HPP powder particles, thusenabling additive manufacturing of HPP-based parts by means of binderjetting at room temperature. The final printed parts can be cured, suchas sintering, to provide the final product. The final product thusobtained has increased mechanical strength, tensile modulus, and elasticmodulus in comparison with the green body prints.

III. Polymers

The three-dimensional form can be made from one or more materials. Incertain embodiments, the three-dimensional form can comprise polymers.Any type of polymer can be used to form the three-dimensional form, andthe polymer can be selected such that the three-dimensional form has thedesired properties. Thus, the polymer can be polyimides, polyketones,reduced form of polyketones, polyethersulfones, and the like.

Polyketone Polymers

In one aspect, the three-dimensional form can be made from a finalpolymer that is a polyketone, such as polyetheretherketone (PEEK),polyaryletherketone (PAEK), polyetherketone (PEK), polyetherketoneketone(PEKK) polyetheretheretherketone (PEEEK), polyetheretherketoneketone(PEEKK), polyetherketoneetheretherketone (PEKEKK), orpolyetherketoneketoneketone (PEKKK). If the polyketone polymer is PEEK,it typically can be obtained by reacting a substantially equimolarmixture of at least one aromatic dihydroxy compound and at least onedihalobenzoid compound or at least one halophenol compound, as shownbelow:

Non-limiting examples of aromatic dihydroxy compounds useful in such aprocess are hydroquinone, 4,4′-dihydroxybiphenyl and4,4′-dihydroxybenzophenone. Exemplary suitable aromatic dihydroxycompounds include bis(hydroxyaryl)alkanes such asbis(4-hydroxyphenyl)methane, bis(2-methyl-4-hydroxyphenyl)methane,bis(3-methyl-4-hydroxyphenyl)methane, 1,1-bis(4′-hydroxyphenyl)ethane,1,2-bis(4′-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)phenylmethane,bis(4-hydroxyphenyl)diphenylmethane,bis(4-hydroxyphenyl)-1-naphthylethane,1,1-bis(4′-hydroxyphenyl)-1-phenylethane,1,3-bis(4′-hydroxyphenyl)-1,1-dimethylpropane,2,2-bis(4′-hydroxyphenyl)propane [“Bisphenol A”],2-(4′-hydroxyphenyl)-2-(3″-hydroxyphenyl)propane,1,1-bis(4′-hydroxyphenyl)-2-methylpropane,2,2-bis(4′-hydroxyphenyl)butane,1,1-bis(4′-hydroxyphenyl)-3-methylbutane,2,2-bis(4′-hydroxyphenyl)pentane,2,2-bis(4′-hydroxyphenyl)-4-methylpentane,2,2-bis(4′-hydroxyphenyl)hexane, 4,4-bis(4′-hydroxyphenyl)heptane,2,2-bis(4′-hydroxyphenyl)octane, 2,2-bis(4′-hydroxyphenyl)nonane,bis(3,5-dimethyl-4-hydroxyphenyl)methane,2,2-bis(3′-methyl-4′-hydroxyphenyl)propane,2,2-bis(3′-ethyl-4′-hydroxyphenyl)propane,2,2-bis(3′-n-propyl-4′-hydroxyphenyl)propane,2,2-bis(3′-isopropyl-4′-hydroxyphenyl)propane,2,2-bis(3′-sec-butyl-4′-hydroxyphenyl)propane,2,2-bis(3′-tert-butyl-4′-hydroxyphenyl)propane,2,2-bis(3′-cyclohexyl-4′-hydroxyphenyl)propane,2,2-bis(3′-allyl-4′-hydroxyphenyl)propane,2,2-bis(3′-methoxy-4′-hydroxyphenyl)propane,2,2-bis(3′,5′-dimethyl-4′-hydroxyphenyl)propane,2,2-bis(2′,3′,5′,6′-tetramethyl-4′-hydroxyphenyl)propane,2,2-bis(3′-chloro-4′-hydroxyphenyl)propane,2,2-bis(3′,5′-dichloro-4′-hydroxyphenyl)propane,2,2-bis(3′-bromo-4′-hydroxyphenyl)propane,2,2-bis(3′,5′-dibromo-4′-hydroxyphenyl)propane,2,2-bis(2′,6′-dibromo-3′,5′-dimethyl-4′-hydroxyphenyl)propane,bis(4-hydroxyphenyl)cyanomethane,3,3-bis(4′-hydroxyphenyl)-1-cyanobutane,2,2-bis(4′-hydroxyphenyl)hexafluoropropane and the like.

Non-limiting examples of dihalobenzoid compounds useful in such aprocess are 4,4′-difluorobenzophenone, 4,4′-dichlorobenzophenone,4-chloro-4′-fluorobenzophenone, and the like; non limitative examples ofhalophenols compounds useful in such a process are4-(4-chlorobenzoyl)phenol and (4-fluorobenzoyl)phenol. Accordingly, PEEKpolymers can be produced by the nucleophilic process as described in,for example, U.S. Pat. No. 4,176,222, or by electrophilicallypolymerizing the starting materials as described in U.S. Pat. No.6,566,484. Other poly(aryl ether ketone)s can be produced by startingfrom other monomers such as those described in U.S. Patent ApplicationNo. 2003/0130476. If the polyketone polymer is PAEK, PEK, PEKK, PEEEK,PEEKK, PEKEKK, or PEKKK, they can be synthesized using known methods.Alternatively and equivalently, a commercially available PEEK, PAEK,PEK, PEKK, PEEEK, PEEKK, PEKEKK, or PEKKK polymer can be used.

The aromatic dihydroxy compounds can comprise one or more alkene groups,one or more thiol groups, or one or more epoxide groups that canparticipate in photo-initiate thiol-ene polymerization. Exemplarystructures are shown below:

It should be appreciated that all compounds having one or more alkenefunctional groups are suitable in conjunction with the teachingspresented herein. However, it is generally preferred that the polyalkeneor alkene compound has at least two alkene groups. The alkene groups maybe provided by allyls, allyl ethers, vinyl ethers, acrylates. Forexample, the olefin moiety can be selected from any suitableethylenically unsaturated group such as allyls, allyl ethers, vinyl,vinyl ether, acetyl, acrylate, methacrylate, maleimide, norbornene orother monomers containing a carbon-carbon double bond, or combinationsthereof. For example, the monomer can be 2,2′-diallylbisphenol-A,O,O′-diallylbisphenol A, 3,3′-diallylbisphenol A, and bisphenol Abisallyl carbonate. Other allylic monomers include diallyl phthalate,diethylene glycol bisallyl carbonate, and diallyl biphenate.

A polyketone polymer can be obtained by reacting a mixture of at leastone monomer having an alkene group, at least one aromatic dihydroxycompound and at least one dihalobenzoid compound or at least onehalophenol compound, as shown below:

The three monomers can be arranged in alternating sequence or in arandom order as blocks of monomers, and can be in any ratio. Preferably,the ketone monomer is about 50% of the reaction mixture. Thus, thereaction mixture can contain a substantially equimolar mixture of thedihydroxy compounds and the dihalobenzoid compound. Thus, the ratio ofthe monomer having the alkene group to the aromatic dihydroxy monomercan be 100:0, 95:5, 90:10, 75:25, 50:50, 25:75, 10:90, 5:95, 0:100, orany other ratio in between.

The HPP can be a ketal of the polyketone polymer, where one or more ofthe carbonyl group (>C═O) can be converted to a diether (>C(OR)₂), whereeach R can be independently selected to be alkyl, alkylene, alkenylene,aryl, or combination thereof. The ketal can be produced by reaction ofthe carbonyl group with, for example, an alcohol, such as a primaryalcohol, a secondary alcohol, a tertiary alcohol, or a combinationthereof. The ketal can be acyclic, cyclic, or spiro cyclic ketal. TheHPP can also be a thioketal, a dithioketal, or a hemiketal of thepolyketone polymer. The ketal, hemiketal, thioketal or dithioketal canbe obtained by reacting the dihalobenzoid compound with the alcohol orwith a thiol, as shown below:

where X can be a hetero atom, such as oxygen or sulfur. Examples ofsuitable monofunctional alcohols include methanol, ethanol, variouslinear and branched isomers of propanol, butanol, pentanol, hexanol,octanol, nonanol, decanol, undecanol, dodecanol, tetradecanol, cetylalcohol, and stearyl alcohol; cycloalkyl alcohols such as cyclohexanol,cyclooctanol, norbornyl alcohol, and the like; alkynyl alcohols such asethynyl alcohol, 3-methylpent-1-yn-3-ol, tetradec-9-ynol, and the like;aryl and alkaryl alcohols such as phenol, benzyl alcohol, toluoyl, xylylalcohol, 5-phenylpentanol, and the like; and alcohols having variousfunctional groups, for example 1,1,1-trichloro-2-methyl-2-propanol,5-fluoro-1-pentanol, 5-amino-1-pentanol, 5-benzyloxy-1-pentanol,5-methoxy-1-pentanol, 3-nitro-2-pentanol, 4-methylthio-1-butanol,6-hydroxyhexanoic acid, lactamide, and the like. In some embodiments,the ketal can by a cyclic ketal formed by the reaction of polyols withthe carbonyl moieties. Examples of suitable polyols include1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol),1,3-propanediol, 1,2,3-propanetriol (glycerol), digylcerol (a mixture ofglycerol dimers coupled at primary and secondary hydroxyl moieties),2,2-dimethyl-1,3-propanediol (neopentyl glycol),3-mercaptopropane-1,2-diol (thioglycerol), dithiothreitol,1,1,1-trimethylolpropane, 1,2-butanediol, 1,3-butanediol,pentaerythritol, cyclohexane-1,2-diol, 1,4-dioxane-2,3-diol, and thelike.

The ketal, hemiketal, thioketal or dithioketal of polyketone can then beused as the HPP for performing the polymerization reaction wherein thefinal polymer is produced. Alternatively, the polymer can first beobtained, and at least one of the carbonyl groups can then be convertedto a ketal, hemiketal, thioketal or dithioketal to provide the HPP.

When the HPP is a ketal of PEEK, the carbonyl group of the ketone moietycan be readily regenerated by hydrolysis using water, acidic solution,heat, light, base catalysis, catalytic hydrogenation, or a combinationthereof. For example, the ketal of PEEK can be converted to the finalpolyketone polymer using a stimulus that is a Brønsted acid or a Lewisacid based reagent. Thus, for example, dilute solution of hydrochloricacid, hydrobromic acid, perchloric acid, acetic acid, sulfuric acid,arylsulfonic acids and hydrates thereof, such as p-toluenesulfonic acidmonohydrate, phosphoric acid or orthophosphoric acid, polyphosphoricacid, sulfamic acid, and the like can be used as the stimulus. In otherembodiments, the acid catalysts employed are aprotic, also referred toas Lewis Acids. Such Lewis acid catalysts can include, for example,titanium tetrachloride, aluminum trichloride, boron trifluoride, stannicchloride, and the like. In some embodiments, more than one type of acidcatalyst is used; thus, blends of one or more of the acids mentionedabove may be used in a mixture to catalyze the reactions.

The polyketone polymer can have a molecular weight such that thethree-dimensional article has high strength and is not brittle. Thepolyketone preferably have an average molecular weight from 1,000 to400,000, more preferably from 10,000 to 350,000, still more preferablyfrom 15,000 to 100,000. Thus, the polyketone can have an averagemolecular weight of about 5,000, 7,000, 10,000, 15,000, 17,000, 19,000,20,000, 22,000, 23,000, 24,000, 25,000, and the like.

In another aspect, the polyketone has an average molecular weight (inDaltons) where the molecular weight distribution is in a range of about500 to about 20,000, preferably a range of about 1,000 to about 10,000,or more preferably, a range of about 3,000 to about 7,000. Thus, thepolyketone can have a molecular weight distribution between about 3,000to about 5,000, about 10,000 to about 13,000, about 15,000 to about18,000, about 23,000 to about 27,000, and the like.

The polyketone HPP can be converted to the final polyketone polymer byexposing it to a stimulus, such as, heat, light, electrolysis, metalcatalyst, or a chemical oxidant, as is known in the art. The light canbe ultraviolet, infrared, visible, or combination thereof. The lightsources are conventionally well known in the art, and include alow-pressure, a medium-pressure or a high-pressure mercury lamp, and ametal halide lamp, a xenon lamp, a cathode tube, a LED, and the like. Inone embodiment, the application of light can be under neutralconditions, optionally in the presence of a catalyst, such as iodine,indium(III) trifluoromethane-sulfonate ortetrakis(3,5-trifluoromethylphenyl)borate, a Lewis acid catalyst, andthe like.

In one aspect, the three-dimensional article made from a final polymerthat is a polyimide polymer. The polyimide polymer can be selected basedon its properties, such as high adhesion properties, high strength,mechanical properties, heat resistance, chemical resistance, electricalinsulation, and the like. The polyimide polymers can be prepared byimidization of the poly(amic acid), using methods known in the art.Thus, for example, the poly(amic acid) can be exposed to a stimulus thatis heat or a chemical imidization reactant. Alternatively, andequivalently, commercially available polyimide polymer can be used.

In another aspect, the three dimensional object can be made from a finalpolymer that is a polysulfone polymer. Polysulfones, as used herein,refers to a family of polymers which contain the subunit-aryl-SO₂-aryl-, more specifically -aryl-SO₂-aryl-O—, as shown below:

where R₁, R₂, R₃, R₄ are independently selected to be an alkyl, analkylene, an aryl, or a halogen. Aromatic polyethersulfones can beprepared, for example, by the reaction of dialkali metal salts ofdiphenols with dihalodiarylsulfones in a solvent. The dialkali salts ofdiphenols may also be produced in situ or may be produced in a separatereaction. The diphenols can be any one as described above or known inthe art. The polysufones includes a polymer of4-[2-(4-hydroxyphenyl)propan2-yl]phenol and4-(4-hydroxyphenyl)sulfonylphenol, commonly known as polysulfone, and apolymer of benzene-1,4-diol and 4-(4-hydroxyphenyl)sulfonylphenolcommonly known as polyethersulfone. Polyethersulfone (PES) is also knownas polyarylethersulfone (PAES) and/or polyphenylsulfone (PPSU). Anothersuitable polysulfone is a copolymer of 4-(4-hydroxyphenyl)phenol and4-(4-hydroxyphenyl)sulfonylphenol, also known as polyphenylsulfone.Other exemplary polysulfones are described in U.S. Pat. No. 5,911,880.

Polyethersulfones can be produced by a variety of methods. For example,U.S. Pat. Nos. 4,108,837 and 4,175,175 describe the preparation ofpolyarylethers and in particular polyarylethersulfones. U.S. Pat. No.6,228,970 describes the preparation polyarylethersulfones with improvedpolydispersity and lower amounts of oligomers. British patent GB1,264,900 teaches a process for production of a polyethersulfonecomprising structural units derived from 4,4′-biphenol, bisphenol-A(4,4′-isopropylidenediphenol), and 4,4′-dichlorodiphenylsulfone. Thus,the polysulfone polymers can be synthesized using known methods.Alternatively, and equivalently, commercially available polysulfonepolymers can be used.

IV. Solid High Performance Polymers

A solid powder of any high performance polymer (HPP) can be obtained asa solid by removal of the solvent. The HPP can be further treated toprovide a powder having the desired particle size distribution orparticle shape. The particle size of the solid HPP can be reduced byutilizing mechanical devices, such as, for example, mortar and pestle,milling, application of ultrasonic energy, by spray drying, or byshearing the particles in a liquid flowing at high velocity in arestricted passage. For example, the solid HPP can be ground using amortar, it can be milled, it can micronized, or it can be nanonized toprovide HPP powder with the desired average particle size. Thus, thesolid HPP can be milled to provide poly(amic acid) powder having anaverage particle size of about 5 microns to about 250 microns, or about10 microns to about 100 microns, and the like. Thus, the HPP powder canhave an average particle size of about 5 microns to about 25 microns,about 20 microns to about 60 microns, about 10 microns to about 20microns, about 20 microns to about 30 microns, about 40 microns to about50 microns, or about 25 microns to about 50 microns.

HPP powder having an average particle size of between 10 nm and 10microns are useful in the compositions described herein. In someaspects, the particles can be nanoparticles having diameters of about 1nm to about 1000 nm, from about 10 nm to about 200 nm, and from about 50nm to about 150 nm. In another aspect, the particles can have a sizerange from about 500 nm to about 600 nm.

The particles can have any shape but are generally spherical in shape.Suitable particles can be spheres, spheroids, flat, plate-shaped, tubes,cubes, cuboids, ovals, ellipses, cylinders, cones, or pyramids. Theparticles can also have random or ill-defined shapes or can beamorphous.

Preferably, the method used to form the powder produces a monodispersedistribution of particles. However, methods producing polydisperseparticle size distributions can be used. If the method does not produceparticles having a monodisperse size distribution, the particles can beseparated following particle formation to produce a plurality ofparticles having the desired size range and distribution. Alternatively,and equivalently, commercially available HPP can be used in thedisclosed methods.

V. HPP Compositions

The HPP compositions comprise a first HPP dissolved in a solvent and asecond HPP that is insoluble in the solvent and is initially present assolid material. The first HPP and the second HPP can be the same polymeror can be different, and can be polyimides, polyketones, reduced formsof polyketones, polyethersulfones, or combinations thereof.

The polyketone polymer or any other high performance polymer (HPP) canbe dissolved in a solvent. The solvent used in carrying out thedisclosed methods is preferably an inert organic solvent that is polar,which can have a high boiling point, and in which the HPP is soluble,but the final polymer is insoluble or has lower solubility. Examples ofthe solvent that can be used include solvents having a nitrogen atom inthe molecule such as N,N-dimethylacetamide, N,N-diethylacetamide,N,N-dimethylformamide, N,N-diethylformamide, N-methyl-2-pyrrolidone,2-pyrolydon, N-methyl-2-pyrolydon, 1,3-dimethyl-2-imidazolidinone, andN-methylcaprolactam; solvents having a sulfur atom in the molecule suchas dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, diethylsulfone, and hexamethyl sulfolamide, tetramethylene sulfone; solventswhich are phenols such as cresol, phenol, and xylenol; solvents havingan oxygen atom in the molecule such as diethylene glycol dimethyl ether(diglyme), triethylene glycol dimethyl ether (triglyme), and tetraglyme;aromatic solvents such as benzene, toluene, ethylbenzene, chlorobenzene,o-xylene, m-xylene, p-xylene, mesitylene, i-propylbenzene,1-chlorobenzene, 2-chlorotoluene, 3-chlorotoluene, 4-chlorotoluene,t-butylbenzene, n-butylbenzene, i-butylbenzene, s-butylbenzene,1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene,1,3-diisopropylbenzene, 1,4-diisopropylbenzene, 1,2-difluorobenzene,1,2,4-trichlorobenzene, 3-methylanisole, 3-chloroanisole,3-phenoxytoluene, diphenyl ether, anisole, and mixtures thereof andother solvents such as acetone, dimethylimidazoline, methanol, ethanol,ethylene glycol, dioxane, tetrahydrofuran, pyridine, andtetramethylurea. In addition, amido based solvents can be used, such asR₃O—(CH₂)_(n)C(O)NR₁R₂, where R₁, R₂, and R₃ can be independentlyselected to be H or lower alkyl, such as methy (Me), ethyl (Et),n-propyl (n-Pr), iso-propyl (i-Pr), n-buty (n-Bu), s-butyl (s-Bu),tert-butyl (t-Bu), and the like. These may be used in combination of twoor more. In one aspect, the solvent can be N-methyl-2-pyrrolidone (NMP),N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), orcombinations thereof.

The solvent can be spearmint oil, fenchone, and can also be a terpene,such as, for example, but are not limited to, menthol, limonene,d-limonene, limonene oxide, geraniol, α-pinene, α-pinene oxide, thymol,menthone, neomenthol, 3-carene, 1-carvol, carvone, carveol, 1,8-cineole(eucalyptol), citral, dihydrocarveol, dihydrocarvone, 4-terpinenol,fenthone, pulegone, pulegol, isopulegol, piperitone, camphor,α-terpineol, terpinen-4-ol, linalool, carvacrol, trans-anethole,ascaridole, safrole, racemic mixtures thereof, isomers thereof, andmixtures thereof. Thus, the solvent can be an acyclic terpene such asterpene hydrocarbons (e.g. ocimene, myrcene), terpene alcohols (e.g.geraniol, linalool, citronellol), or terpene aldehydes and ketones (e.g.citral, pseudoionone, β-ionone). The solvent can be a monocyclicterpenes, such as terpene hydrocarbons (e.g. terpinene, α-terpinene,terpinolene, limonene), terpene alcohols (e.g. terpineol, thymol,menthol), or terpene ketones (e.g. pulegone, carvone). The solvent canbe a bicyclic terpene such as terpene hydrocarbons (e.g. carane, pinane,bornane), terpene alcohols (e.g. borneol, isoborneol), or terpeneketones (e.g. camphor).

The solvent can be alloocimene, alloocimene alcohols, anethole,anisaldeyde, camphene, camphor, 10-camphorsulphonic acid, 3-carene,citral, cintronellal, citronellol, p-cymene, dipentene(p-mentha-1,8-diene), geraniol, 7-hydroxydihydrocitronellal,7-methoxydihydro-citronellal, isoborneol, isobornyl acetate,p-menthan-8-ol, p-menthan-8-yl acetate, menthol, menthone, nopol,ocimene, dihydromycenol, 3,7-dimethyl-1,6-octadiene, pinane, 2-pinanehydroperoxide, pine oil, α-pinene, β-pinene, 2-pinanol, α-terpineol,β-terpineol, γ-terpineol, terpin hydrate, α-terpinyl acetate, andmixtures thereof.

The solvent can be an aqueous solvent, such as water or a mixture ofwater and an organic solvent, acid, base, and the like.

The HPP can be dissolved in a solvent, such as an organic solvent or anaqueous solvent. An organic solvent can be NMP, DMF, DMAc, a terpene,toluene, spearmint oil, fenchone, or any of the others described indetail above used alone or as a mixture of two or more solvents. The HPPcan be dissolved to provide a 1% solution, a 2% solution, a 3% solution,a 4% solution, a 5% solution, a 6% solution, a 7% solution, a 8%solution, a 8% solution, a 10% solution, a 15% solution, a 20% solution,a 25% solution, a 30% solution, a 35% solution, a 40% solution, a 45%solution, a 50% solution, and the like.

The solution of dissolved HPP can be used to bind insoluble particles ofa polymer or a HPP. In one aspect, to the solution of dissolved HPP isadded a second HPP that is present as a solid and is soluble in thesolvent. The resultant mixture can be subjected to conditions such thata paste is obtained. The paste can be molded or extruded to generateobjects from HPPs that were cast from non-reconfigurable designs.

The insoluble particles of a polymer or a HPP can have any desiredparticle size as described in detail above, such as, for example, havingan average particle size of about 5 microns to about 250 microns, orabout 10 microns to about 100 microns, and the like. The exactparticulate dimensions of the materials are not generally critical.However, in certain aspects, the particulate size of the materials maybe important. In particular, the particulate size of the materials maybe important in those aspects wherein type of printing equipmentdictates that either relatively small particle size or larger particlesize is desired. For example, the particle size can be important toallow easier flow of the material during molding or extrusion processes.

In another aspect, the particle size of the insoluble particles of apolymer or a HPP can be selected to obtain desired properties of the 3Dproduct. For example, the particle size can be selected that providesfor better shape retention, greater cohesiveness, greater strength,greater mechanical or structural integrity, and the like, of the 3Dproduct. In such aspects, the particle size of the insoluble particlescan beneficially be smaller, such as 5 microns, 10 microns, 20 micronsand the like. According to this aspect, and while not wishing to bebound by any particular theory, it is believed that the small size ofthe particles provides for the 3D product having better mechanicalproperties, such as greater strength.

As one of skill in the art will recognize, a correlation can be createdbetween the particle size of the insoluble particles of a polymer or aHPP and the measured properties of the 3D product. Examples of measuredproperties include, but are not limited to, glass transition temperature(Tg), decomposition temperature, Young's modulus, elastic storagemodulus, and the like. The method takes as an input the average particlesize of the polymer and the measured mechanical properties of the 3Dproduct. The correlation can then be used to select the particle sizefor use in the 3D printing method wherein a 3D product with thepredetermined mechanical properties can be produced.

In another aspect, to the solution of dissolved HPP is added particlesof insoluble HPP, and the resultant mixture can be subjected toconditions such that a viscous solution is obtained. The viscosity ofthe composition can typically be from about 0.1 centipoise (cp) to about100 cp, preferably about 1 cp to about 50 cp. The viscosity of the HPPcompositions can be adjusted by adding more or less solvent, byselecting the concentration of HPP solution, or any other means known inthe art. The viscosity of the composition is such the composition flowsthru the extrusion apparatus and at the extrusion temperature.

VI. Molding

The 3-dimensional objects can be formed by a molding process. Thus, theshaping and drying step can comprise operations of casting or moldingthe HPP compositions in cavities of suitable shape or cross section. Theterm molding should be taken in its broadest sense and covers any typeof conformation, such as casting in an open mold, extrusion through adie and cutting of the extrudate, injection molding (injectioncompression molding, gas-assisted injection molding and insert moldingetc.), blow molding, rotational molding, extrusion molding, pressmolding, transfer molding, and the like.

The HPP composition can be placed into a mold or extrusion-molding, anda 3D article having a desired shape can be produced. Optionally, astimulus, such as heat or light can be applied.

VII. Printing

A solution of HPP composition and a powder of a HPP can be used in aprocess to create three-dimensional articles using a three-dimensionalprinting system. The HPP composition, as described in detail above,comprises a first HPP dissolved in a solvent and a second HPP present asa solid, wherein the mixture thus obtained is mixed to provide a viscoussolution. A three-dimensional printing system can have a computer, athree-dimensional printer, and means for dispensing the HPP powder andthe HPP composition. The three-dimensional printing system canoptionally contain a post-printing processing system. The computer canbe a personal computer, such as a desktop computer, a portable computer,or a tablet. The computer can be a stand-alone computer or a part of aLocal Area Network (LAN) or a Wide Area Network (WAN). Thus, thecomputer can include a software application, such as a Computer AidedDesign (CAD)/Computer Aided Manufacturing (CAM) program or a customsoftware application. The CAD/CAM program can manipulate the digitalrepresentations of three-dimensional articles stored in a data storagearea. When a user desires to fabricate a three-dimensional article, theuser exports the stored representation to a software program, and theninstructs the program to print. The program prints each layer by sendinginstructions to control electronics in the printer, which operates thethree-dimensional printer. Alternatively, the digital representation ofthe article can be directly read from a computer-readable medium (e.g.,magnetic or optical disk) by printer hardware.

Typically, a first layer of the HPP solid or powder can be depositedonto a build plate. The deposited HPP solid or powder can be heated to atemperature that is less than about 200° C., and can be in the range ofabout 30° C. to 170° C., preferably in the range of about 50° C. toabout 150° C. The temperature is selected such that it is below that ofwhich polymerization of the HPP occurs, but aids in the polymerizationof the HPP when the HPP composition is added. Thus, the deposited HPPsolid or powder can be heated to a build temperature of about 40° C.,50° C., 60° C., 70° C., 80° C., 100° C., 110° C., 120° C., 130° C., 140°C., 150° C., 160° C., and the like. The deposited HPP solid or powdercan be heated to the desired temperature using any of the known contactor non-contact methods, such as for example, using a heater including,but not limited to, a microwave heater, an infrared heater, an inductionheater, a micathermic heater, a solar heater, a heat exchanger, an archeater, a dielectric heater, a gas heater, a plasma heater, a lampheater, an infrared heater or any combination thereof, by using a heatedplate or a heated roller, or by locally heating the HPP solid or powderusing a laser or a laser diode, such as, for example, a scanning carbondioxide laser.

The first layer of the HPP solid or powder can be deposited onto thebuild plate using any of the known methods, such as, using a roller,using a scraper, using mechanical means, and the like. Thus, forexample, a measured quantity of the HPP solid or powder can bedistributed over the build plate to a desired thickness using a roller.In another aspect, the layer of the PEEK powder can have a thickness ofabout 0.1 nm to less than 500 nm, of about 5 nm to about 250 nm, ofabout 0.2 nm to about 100 nm, of about 0.3 nm to about 50 nm, of about0.3 nm to about 25 nm, of about 0.3 nm to about 20 nm, of about 0.3 nmto about 15 nm, of about 0.3 nm to about 10 nm, of about 0.3 nm to about5 nm, and the like. In yet another aspect, the layer of the PEEK powdercan have a thickness of about 10 microns to less than about 500 microns,of about 25 microns to about 250 microns, or of about 50 microns toabout 100 microns.

The method of printing a three-dimensional article layer by layer isillustrated in FIG. 1A-1D. In FIG. 1A, the roller 5, deposits HPP solidas a powder from one or more powder bed reservoir 2 to the powder bed 1.The build plate 3 can move in vertical direction as needed. The head 4prints a HPP composition on the powder bed 1. The HPP compositioncomprises a HPP dissolved in a solvent. The solvent can be any of thesolvents disclosed above, such as, for example, a solvent with a lowvapor pressure and is food-safe or GRAS, such as spearmint oil,α-terpinene, limonene, α-pinene, fenchone, and combinations thereof. TheHPP composition can be printed onto the powder bed on the build plate byany printing mechanism. For example, printing may comprise inkjetprinting, screen printing, gravure printing, offset printing,flexography (flexographic printing), spray-coating, slit coating,extrusion coating, meniscus coating, microspotting, pen-coating,stenciling, stamping, syringe dispensing and/or pump dispensing theactivator solution in a predefined pattern.

In one aspect, the three-dimensional article can be formed by using asyringe or syringe-like dispenser to print the HPP composition on abuild plate, as shown in FIG. 1B. FIG. 1B shows a single layer beingpatterned. Typically, the syringe deposits a first layer of the HPPcomposition onto the build plate in a two-dimensional pattern. Thesyringe, such as Norm-Ject Luer Lock plastic syringes, preferably has asmall orifice diameter, thereby enabling the formation of electronicfeatures having a fine minimum feature size. In one aspect, the syringeor other deposition tool includes a deposition orifice having a diameterof not greater than about 200 μm, more preferably not greater than 100μm, more preferably not greater than 50 μm and even more preferably notgreater than about 25 μm. The print speed is dependent on feature sizeand materials used, and can be easily determined by one of skill in theart and adjusted as desired, and can be between about 1 mm/sec to about1000 mm/sec, about 5 mm/sec to about 500 mm/sec, about 20 mm/sec toabout 100 mm/sec, or about 10 mm/sec to about 50 mm/sec. Thus, the printspeed can be between about 5 mm/sec to about 30 mm/sec, or between about10 mm/sec to about 20 mm/sec.

The printing system can have a printing mechanism for printing a HPPcomposition onto the HPP solid or powder. For example, printing maycomprise inkjet printing, single jet printing, screen printing, gravureprinting, offset printing, flexography (flexographic printing),spray-coating, slit coating, extrusion coating, meniscus coating,microspotting, pen-coating, stenciling, stamping, syringe dispensingand/or pump dispensing the HPP solution in a predefined pattern, Thus,the three-dimensional article can be formed by using an ink jet typeprint cartridge to deposit the HPP composition from the ink jets onto abuilt plate. Ink jet print heads that can be used in the disclosedmethods include MI-15420, MI-12480, MI-12420, and MI-11801, allavailable from Ricoh Printing Systems America, Inc.

Typically, an ink-jet nozzle prints a two-dimensional pattern of a HPPcomposition onto the HPP powder bed deposited on a built plate. Theprinted composition can be contacted with a stimulus wherein the HPP isconverted, at least partially, to the final polymer. As described indetail below, the selected stimulus is dependent on the HPP, and can beheat, chemical oxidants, acids, light, electrolysis, metal catalysts,and the like. After a preset period of time that is selected to allowthe HPP to partially or fully convert to the final polymer, the nextlayer of the HPP powder can be deposited to form a powder bed, and thesteps repeated. Thus, a 3D article can be manufactured layer by layer.

Optionally, the printed solution can be exposed to a stimulus to form apolymer layer of the three-dimensional article. For example, thestimulus can be heat or a chemical imidization reactant. When the HPP isa ketal, the stimulus can be a Brønsted acid, a Lewis acid, or light.When the HPP is a polysulfide, the stimulus can be an oxidant, such asan organic peroxy acids, an organic peroxides, an inorganic peroxides,or mixtures thereof. When the HPP contain a cross-linking moiety, thestimulus can be light, such as visible light or UV light.

In FIG. 1C, the roller 5, as depositing mechanism, deposits HPP powderfrom a powder bed reservoir 2 to the powder bed 1. FIG. 1D shows thatthe HPP powder has formed a new powder bed layer, and the process can berepeated to print a three-dimensional article layer by layer.

In another aspect, the three-dimensional article can be formed bypatterning successive layers on a build plate using lithography. Thethree-dimensional article can be formed by applying a layer of HPPpowder to form a powder bed on a build plate. Heating the powder bed toa predetermined temperature. Printing HPP composition on the powder bedthrough a patterned imaging plate, such as a mask or reticle. The HPPcomposition can be deposited using any known methods, such as, forexample, spraying, by using a syringe, by using an inkjet print head,and the like.

The region that received the jetted HPP composition is allowed topolymerize by maintaining the temperature for the duration of the holdtime. Thus, the HPP powder exposed to the HPP composition can be allowedto stay at the hold temperature or the present temperature for about 1minute to about 2 hours, preferably about 5 minutes to about 30 minutes,more preferably about 8 minutes to about 15 minutes, or from about 1 secto about 300 sec, preferably about 5 sec to about 30 sec, morepreferably about 8 sec to about 15 sec. Thus, the HPP powder exposed tothe HPP composition can be allowed to stay on the plate at the holdtemperature or the present temperature for hold time of about 7 minutes,about 8 minutes, about 9 minutes, about 10 minutes, about 11 minutes,about 12 minutes, about 13 minutes, about 14 minutes, about 15 minutes,and the like. Without being bound to a theory, the holding period allowsvolatile components of the fluid, such as the solvent, to evaporate, andthe layer to polymerize or at least partially polymerize to form thefinal polymer. Thus, the holding time is selected such that the HPP canpolymerize to the final polymer.

The process is repeated with a new layer of the HPP powder being appliedover the top of the previous layer on the build plate. The next crosssection of the desired product is then printed with the HPP compositionbeing printed onto the new powder layer.

The previous steps of applying a layer of the HPP powder to the buildplate, depositing a solution of activator and allowing it to stay on thebuild plate at a predetermined temperature and for a predeterminedperiod of hold time are repeated until the final article is completed.The unreacted HPP powder can be removed, if desired, at any time duringthe process. Thus, a three-dimensional article can be built layer bylayer by depositing a series of HPP layers on a build plate to form apowder bed, and printing the HPP composition onto the powder bed.

In another aspect, a HPP composition for use in a process to createthree-dimensional articles using a three-dimensional printing system canbe deposited onto a build plate, and a stimulus can be printed using thethree-dimensional printing system to create the three-dimensionalarticle. The HPP composition, as described in detail above, comprises afirst HPP dissolved in a solvent and a second HPP present as a solid,wherein the mixture thus obtained can be deposited onto the build plateas the powder bed. If the stimulus is a photoinitiator, then exposure tolight, such as UV light, can be used to create the 3D article.

In another aspect, a HPP powder mixed with stimulus can be depositedonto a build plate, and a stimulus can be printed using thethree-dimensional printing system to create the three-dimensionalarticle. A HPP composition comprising a HPP dissolved in a solvent canbe printed on the HPP powder deposited onto the build plate. The solventcan be any of the solvents disclosed above, such as, for example, asolvent with a low vapor pressure and is food-safe or GRAS, such asspearmint oil, α-terpinene, limonene, α-pinene, fenchone, andcombinations thereof. The HPP composition can be printed onto the powderbed on the build plate by any printing mechanism. If the stimulus is aphotoinitiator, then exposure to light, such as UV light, can be used tocreate the 3D article. Optionally, the three-dimensional printing systemcan be used to print another stimulus, such as an acid, a base, or aBrønsted acid/base, in a pattern onto the 3D article, thereby furthercuring selected regions. The process can be used to make 3D articleshaving heterogeneous parts with differing crosslinked density.

VIII. Curing

The three-dimensional article obtained using the methods and processesdescribed above can be cured to obtain the final three-dimensionalarticle. The curing of the article can be done while it is attached tothe build plate, or the curing of the article can be done by separatingit from the build plate first and then curing it. In the curing process,the unreacted prepolymer is converted to the final polymer. Thus, forexample, if the prepolymer is poly(amic acid), the unreacted poly(amicacid) is converted to the polyimide polymer via imidization during thecuring process.

In one aspect, during the curing process, the poly(amic acid) can beconverted to a polyimide polymer by dehydration wherein water iseliminated. Imidization to produce the polyimide, i.e. ring closure inthe poly(amic acid), can be effected through thermal treatment, chemicaldehydration or both, followed by the elimination of a condensate. Thepolyimide polymer can be produced by a polymerization/imidizationreaction according to a known method such as a thermal imidization byheat treatment accompanied by solvent removal and a chemicalimidization, for example, by treatment with acetic anhydride accompaniedby solvent removal.

In one aspect, chemical imidization can be used to convert the poly(amicacid) to the polyimide. Chemical imidization can be carried out usingknown agents, such as acetic anhydride; orthoesters, such as, triethylorthoformate; coupling reagents, such as, carbodiimides, such asdicyclohexylcarbodiimide (DCC) and diisopropylcarbodiimide (DIC),boronic acid, boronic esters, and the like.

In yet another aspect, the curing of compounds such as polyimide andcompositions or articles comprising polyimides can be accomplished bycuring at elevated temperatures. The curing can be by isothermal heatingat a temperature greater than about 190° C., preferably greater thanabout 250° C., more preferably greater than about 290° C. Thus, thethermal imidization can be carried out at about 280° C., about 290° C.,about 300° C., about 310° C., about 320° C., about 350° C., about 375°C., and the like. The curing temperature is selected such that poly(amicacid) is converted to a polyimide and the temperature is below the glasstransition temperature or the melting point of the polyimide.

Alternatively, the curing at elevated temperatures can be performed inan isothermal staging process. As an example, such an isothermal stagingprocess can start by heating the material to be cured to 180° C. to 220°C., such as to about 200° C., for some time, typically 1 to 2 hours.However, also less time, such as less than 1 hour, or less than 30minutes, can be used. Further, also longer times, such as up to 10 hoursmay be used. Subsequently, the temperature can be increased in steps.Each step may correspond to an increase of the temperature of 10° C. to50° C. Further, each step may have duration of 30 minutes to 10 hours,such as 1 to 2 hours. The last step may be curing at a temperature of250 to 400° C., such as at about 300° C. In an isothermal stagingprocess the duration of each isothermal step may decrease as thetemperature increases. A further example of an isothermal stagingprocess, is a process starting at 150° C. in which the temperature isincreased by 25° C. every hour until 300° C. is reached.

Curing the final product at elevated temperatures can be performed withcontinuously increasing temperature. Preferably, the heating rate isslow initially but gradually increased as the temperature increases.Thus, for example, the heating process can start at 150° C. and thetemperature is increased continuously until 300° C. or above is reached.

The time of heating for thermal imidization can be about 0.1 h to about48 h, such as 0.5 h to 15 hours, or 0.5 h to 5 h.

The polyimide polymer thus produced has a tensile strength at break of150 MPa or higher, more preferably 200 MPa or higher, particularlypreferably 250 MPa or higher. The tensile strength can be measured usingknown methods, such by using the Instron Load Frame instruments.

The polyimide polymer thus produced has a tensile modulus of 1.5 GPa orhigher, more preferably 2.0 GPa or higher, particularly preferably 2.5GPa or higher.

The three-dimensional articles prepared using the methods, processes,and systems of the invention are useful in circuit applications, medicalapplications, transportation applications, and the like. For example thethree-dimensional articles can be a printed circuit, an insulator, amedical construct such as an orthotic device, a dental implant,prosthetic sockets, and the like, seal rings, washers, and the like.

EXAMPLES

The examples below are offered for illustrative purposes only, and arenot intended to limit the scope of the present invention in any way.Efforts have been made to ensure accuracy with respect to numbers used(e.g., amounts, temperatures, etc.), but some experimental error anddeviation should, of course, be allowed for.

Commercial powder PEEK was purchased from Evonik with a diameter of 20μm or Victrex with a diameter of 50 and utilized as received. Mechanicalproperties of the prepared PEEK samples were examined by dynamicmechanical analyzer (DMA) 8000 from PerkinElmer. Sinusoidal forces wereapplied to rectangular samples within linear viscoelastic regions(strain 0.03 mm) under constant frequency (1 Hz for rectangular samplesand 10 Hz for crosslinked film samples) as a function of temperaturefrom 24° C. to 270° C. (150° C. for crosslinked films) at 3° C./min.Glass transition temperature (T_(g)) was determined to be a tan(δ) peak.Tensile testing of a dog bone sample (thickness of 3.1 mm and width of5.2 mm) was performed by Instron 5500R with an extensometer (initiallength of 25.4 mm) at a rate of 1 mm/min. Tensile (or Young's) moduluswas calculated from the slope in the plot of tensile stress as afunction of strain. Differential scanning calorimetry (DSC) studies ofthe commercial powder PEEK and the synthesized BPA-PEEK were conductedby a TA DSC Q20 calorimeter under nitrogen. Powder samples sealed inaluminum pans were first heated from room temperature to 380° C. at 10°C./min to remove any thermal history in the samples, and cooled to roomtemperature. Then the samples were second heated to 380° C. at 10°C./min, and heat flow as Watt from this second heating was recorded.Molecular weights of the synthesized BPA-PEEK were determined by gelpermeation chromatography (GPC) equipped with three MZ gel 10 μm columnsof pore sizes of 10³, 10³, and 10⁵ Å respectively, a DAWN-HELOS II18-angle multi-angle laser light scattering detector, and an OptiLabT-rEx refractive index detector from Wyatt Technologies Corporation. THFwas used as eluent at a rate of 1 mL/min. The absolute weight averagemolecular weights were determined by a do/dc value which was measured byassuming the 100% mass recovery of the polymers after passing thecolumns. Thermogravimetric analysis (TGA) of powder PEEK and BPA-PEEKwas conducted by a TA TGA Q50 from room temperature to 800° C. at 10°C./min.

Example 1

Synthesis of High Molecular Weight BPA-PEEK Polymers

PEEK polymer having the following structure:

was synthesized. Bisphenol A (BPA, 11.46 g, 50 mmol),4,4′-difluorobenzophenone (10.91 g, 50 mmol), and potassium carbonate(7.6 g, 55 mmol) were mixed in 100 mL of dry DMSO and 50 mL of drytoluene in a three neck flask connected with a N₂ gas inlet and DeanStark trap with a condenser. This mixture was stirred in an oil bath at150° C. (up to 160° C.) for 2 h, and then 170° C. (up to 180° C.) for 15h (to 24 h). As polymerization proceeded, a solid product precipitated.The solution was cooled to room temperature, and the solvent wasdecanted to provide the solid product. The solid product was purified bydissolving the solid product in DCM (˜200 mL), and adding cold methanolin an ice bath to precipitate the polymer solid. The resulting solid waswashed with water to remove any remaining K₂CO₃ and filtered. Forfurther purification, after drying, the solid product was dissolved inand adding cold methanol in an ice bath to precipitate the polymersolid. The polymer solid was air dried to provide a lightly brown to tansolid as a final product (21 g, 94% yield).

Example 2

Synthesis of Polymers Comprising an Alkene Moiety

PEEK polymer having the following structure:

was synthesized. To a 100 mL flask was added 4,4′-difluorobenzophenone(3.30 g, 15.12 mmol), bisphenol A (1.72 g, 7.53 mmol), 2,2′-diallylbisphenol A (2.33 g, 7.55 mmol) and DMSO (30 mL). The suspension washeated to 50° C. until all solids dissolved. To this solution was addedtetramethylammonium hydroxide pentahydrate (5.54 g, 30.57 mmol) and thereaction temperature increased to 120° C. After 90 minutes, the reactionwas cooled to room temperature and the liquid decanted. The remainingsolids were dissolved in dichloromethane and precipitated into methanolto give the alkene-containing PEEK (4.69 g, 70% yield). Analysis by¹H-NMR spectroscopy showed a ˜1:1 ratio of BPA:diallyl BPA units.

Example 3

Synthesis of Polymers Comprising an Epoxide Moiety:

To a solution of the alkene-containing PEEK prepared in Example 1 (4.69g, 10.51 mmol) in dichloromethane (75 mL) was added m-CPBA (5.21 g,21.13 mmol). After stirring for 2 hours, the polymer was precipitatedinto methanol to give the epoxy-PEEK polymer (4.23 g, 87% yield). GPCanalysis showed M_(n)=21.6 KDa; M_(w)=39.4 KDa;

=1.82.

Example 4

Photo-Crosslinking of Epoxy-PEEK in Spearmint Oil:

The epoxy-PEEK polymer prepared in Example 2 was dissolved in spearmintoil to provide a 7 weight % epoxy-PEEK solution. The control experimentdid not have the epoxy-PEEK polymer present. To the epoxy-PEEK solutionwas added triarylsulfonium photoinitiator at either 1 weight % or 8weight %, para-toluenesulfonic acid (PTSA) at either 0, 0.1, Or 0.1weight %, fluoroantimonic acid hexahydrate (HSbF₆.6H₂O) at 0 or 1 weight%, and trifluoroacetic acid (TFA) at 0 or 1 weight %. Approximately 0.3mL of the solution was deposited onto a glass slide and either exposedto UV light or not exposed to UV light using a 100-W lamp with emissionwavelength of 365 nm. The time required for the material to harden andbecome free-standing when removed from the glass slide was recorded. Thedata is summarized in Table 1.

TABLE 1 Cure time for cross-liking of epoxy-PEEK in spearmint oil as thesolvent. epoxy- photo- Cure PEEK initiator pTSA Time entry (wt %) (wt %)(wt %) HSbF₆•6H₂O TFA UV (min) 1 7 — 1 — — off — 2 7 — — 1 — off 1 3 0 —— 1 — off — 4 7 — — — 1 off — 5 7 1 — — — on — 6 7 1 1 — — on 7 7 7 1 —1 — on 1 8 7 1 — — 1 on 7

The results showed that addition of an acid in the absence of aphoto-initiator was not effective in reducing the cure time. The data inTable 1 shows that pTSA alone was not affective (entry 1), nor was TFA(entry 4). However, when HSbF₆.6H₂O was used, cure time of 1-minute wasobserved even in the absence of the photo-initiator (entry 2).Furthermore, the combination of acid and photo-initiator in spearmintoil was more effective than either activating agent alone. For example,neither the photo-initiator/UV light nor pTSA individually led to curingof the epoxy-PEEK, but when combined (entry 6) a successful 7-minutecure time was observed. Similar synergistic effect was observed from TFAwith the photo-initiator (entry 8). The combination of HSbF₆.6H₂O withthe photo-initiator (entry 7) had about the same cure time as the use ofHSbF₆. 6H₂O alone (entry 2).

Example 5

Photo-Crosslinking of Epoxy-PEEK in Terpene Solvents:

The photo-crosslinking of epoxy-PEEK polymer in terpinene solvents wasperformed as detailed in Example 4, except the solvent was spearmint oiland a terpene. The time required for the material to harden and becomefree-standing when removed from the glass slide was recorded. The datais summarized in Table 2.

TABLE 2 Cure time for cross-liking of epoxy-PEEK in mixture of spearmintoil and a terpene as the solvent. epoxy- photo- Cure PEEK initiator pTSATime entry solvent (wt %) (wt %) (wt %) HSbF₆•6H₂O TFA UV (min) 1α-terpinene/spearmint 7 1 — — — yes 30 2 oil (1:1.2 7 8 — — — yes 10v/v) 3 limonene/spearmint 7 1 — — — yes 15 4 oil (1:1.3 7 8 — — — yes 5v/v) 5 α-pinene/spearmint 7 1 — — — yes 30 6 oil (1:1.9 7 8 — — — yes 15v/v)

The results showed that addition of a terpene as a co-solvent reducingthe cure time when compared to spearmint oil as the solvent. The use ofα-terpinene, limonene, and α-pinene as co-solvents (entries 1-6) withspearmint oil each gave better results than using spearmint oil alone(Table 1, entry 5, no curing observed). The low polarity of theco-solvents necessitated some spearmint oil to dissolve the epoxy-PEEKat 7 wt %. Increasing the wt % of photo-initiator from 1 to 8 wt % wasobserved to reduce the cure time for each of the three solvent mixtures.

Example 6

Photo-Crosslinking of Epoxy-PEEK in Fenchone:

The photo-crosslinking of epoxy-PEEK polymer in fenchone as the solventwas performed as detailed in Example 4. The time required for thematerial to harden and become free-standing when removed from the glassslide was recorded. The data is summarized in Table 3.

TABLE 3 Cure time for cross-liking of epoxy-PEEK in fenchone as thesolvent. epoxy- photo- pTSA PEEK initiator (wt Cure entry (wt %) (wt %)%) HSbF₆•6H₂O TFA UV Time 1 7 — 1 — — off — 2 7 — — 1 — off 30 sec 3 0 —— 1 — off — 4 7 — — — 1 off — 5 7 1 — — — on 15 sec 6 7 1 1 — — on 30sec 7 7 1 — 1 — on 30 sec 8 7 1 — — 1 on  1 min

Fenchone is a food-safe solvent that has the polar carbonyl functionalgroup but lacks the α,β-unsaturation that could lead to reactions withradical species. The data show that the use of fenchone as the solventresults in much shorter cure time compared with spearmint oil andsolvent system where a mixture of spearmint oil and a terpene was used.Specifically, cure time of 30-second was observed when HSbF₆. 6H₂O wasused even without the photo-initiator (entry 2). Even more rapid15-second cure times were observed when the photo-initiator was used(entry 5). The use of a photo-initiator and an acid (entries 6, 7, and8) did not increase the cure time to less than 30 sec. However, the datain Table 3 shows that the use of fenchone as the solvent forcross-linking provides much faster cure times.

Example 7

Preparation of Model Products Using PEEK Polymer:

The BPA-PEEK polymer prepared in Example 1 was dissolved in spearmintoil to provide a 6 weight % to 8 weight % BPA-PEEK solution. To 2 mL ofthe BPA-PEEK solution was added powder PEEK (1 g, purchased from Evonic)with a diameter of approximately 20 μm, and the mixture was stirredovernight at room temperature to provide a paste (semi-solid, FIG. 2A).The paste was molded to rectangular shapes (or a dog bone shape) ofcrosslinked polysiloxane (3.8 mm (T)×5.7 mm (W)×28.6 mm, FIG. 2B). Themolded shape placed in an oven, and the temperature was increased at arate of about 0.5° C./min to 120° C. (range from 100° C. to 150° C.) toprevent any cracking from fast heating to high temperature. Afterheating for 3 h, the rectangular product cast in the mixture of PEEKpowder and BPA-PEEK was removed from the mold (FIG. 2C). The castedproduct was further dried at 220° C. for 3 h to remove any remainingsolvent. The dried product was baked at high temperature by two methodsas follows. In the first method, the dried product was baked at 332° C.(temperature range: up to 345° C.), which is below the meltingtemperature of the powder PEEK (345° C.), for 2 to 3 h. In the secondmethod, the dried product was baked them above 360° C., above themelting temperature of the powder PEEK, for a short period time (i.e. 5mins). The samples were heated from 220° C. to 365° C. (temperaturerange: 360° C. to 380° C.) at the rate of about 7° C./min, and kept at365° C. for 5 mins (up to 20 mins depending on the size of samples) andcooled to room temperature (FIG. 2D). The product baked by the secondmethod (baked above 360° C.) should be cooled to 150° C. slowly (for atleast one hour) to minimize any distortion or bending of the sample. Ifthe bottom side of the rectangles was not fully melted and the samplewas bent, the sample was reversed up to down and baked at 365° C. foradditional 5 mins. After baking at 365° C., the dimensions of the samplewere reduced to 2.9 mm×5.0 mm×22.4 mm.

To study the effect of soaking on the mechanical properties of the PEEKsamples, the first baked, rectangular sample after DMA experiment wasimmersed into the PEEK solution in spearmint oil (6 weight % or 8 weight%) for 30 mins. The sample was dried in the air at room temperature, andfurther dried in a heating oven at 220° C. for 2 hrs. Then the samplewas baked at 365° C. for 5 mins. This procedure is called “1^(st)soaking and 2^(nd) baking” in this study. This sample was examined byDMA. The area of the rectangular sample for DMA experiment keptidentical. Then the same sample after DMA was immersed in the PEEKsolution, dried and baked under the identical conditions, which is call“2^(nd) soaking and 3^(rd) baking.” The results are shown in FIG. 3A-3B.Additional soaking and baking cycles showed an increase in the elasticstorage modulus (E′) of 535 MPa, however, additional soaking and bakingcycles did not improve E′ (FIG. 3A). In addition, the glass transitiontemperature, Tg, was not changed by the soaking and baking cycles (FIG.3B).

Example 8

Preparation of 3D PEEK Products by Syringe Printing:

The BPA-PEEK polymer prepared in Example 1 was dissolved in spearmintoil to provide a 6 weight % BPA-PEEK solution. To 7.6 mL of the BPA-PEEKsolution was added powder PEEK (2.5 g, purchased from Evonic) with adiameter of approximately 20 μm and the mixture was stirred overnight atroom temperature to provide viscous mixture of powder PEEK and BPA-PEEKsolution.

Using a 1 mL syringe, this mixture was printed on a glass slide at roomtemperature or a glass slide heated to around 50° C. by placing it on ahot plate. Multiple layers were added on the printed areas. In somecases, up to 10 layers were added. The printed samples were dried on ahot plate for at least 3 h. FIG. 4A shows a multiple-layered 3D log-likestructure, while FIG. 4B shows the letter “W” having multiple layers,both prepared by the method described above.

Example 9

Preparation of 3D PEEK Products Using Different Particle Sizes:

The BPA-PEEK polymer prepared in Example 1 and having high molecularweight (Mw=121 kDa) was dissolved in spearmint oil to provide a 8 weight% BPA-PEEK solution. To 2 mL of the BPA-PEEK solution was added powderPEEK (2.5 g, purchased from Evonic) with a diameter of approximately 20μm or approximately 50 and the mixture was stirred overnight at roomtemperature to provide a paste. As described in Example 4, the paste wasmolded to rectangular shapes. The molded shape were removed from themold and placed in an oven, and the temperature was increased at a rateof about 0.5° C./min to 120° C. (range from 100° C. to 150° C.). Afterheating for 3 h, the casted product was further dried at 220-230° C. toremove any remaining solvent. The dried product was baked at 370-385°C., above the melting temperature of the powder PEEK, for a short periodtime (i.e. 5-20 mins), and then cooled to 150° C. slowly to minimize anydistortion or bending of the sample.

The 3D product thus obtained using high molecular weight PEEK anddifferent particle size was analyzed by DMA. The glass transitiontemperature (Tg) was determined from a plot of temperature versusTan(delta) (FIG. 5). The 3D products produced above using eitherapproximately 20 μm or approximately 50 μm particle size had Tg valuesof 174-177° C. For comparison, Tg for commercial PEEK samples fromVictrex was determined to be 183° C. The results indicate that strengthof the 3D product can be varied by selecting the appropriate particlesize of the polymers. In addition, the green body objects obtained usingthe 20 μm PEEK were more robust. Thus, a particle size can be selectedthat provides a 3D product with the desired mechanical properties.

The 3D product made using 20 μm polymer was tested using an Instron loadframe to determine the Young's modulus and tensile stress at break. Theresults are shown in FIG. 6. The slope of the stress-versus-strain givesa Young's modulus of 1.33 GPa. The tensile stress at break was found tobe 29.6 MPa. In comparison, the tensile strength for commercial PEEK istypically 90-100 MPa.

Example 10

Preparation of 3D PEEK Products by Jetting of Epoxy-PEEK in Fenchone:

Based on the measured viscosity profile, we proceeded to perform initialexperiments to jet the solution of epoxy-PEEK and UV photoinitiatorusing the Gen4L head. With the Gen4L head temperature set at 65° C., thesolution was successfully jetted onto a microscope slide. The microscopeslide onto which we jetted the fenchone solution was placed under an UVlamp and cured to a gel in under 1 minute. The gel hardened to a solidas a result of ongoing exposure to ambient room lighting. It should benoted that when printing with the fenchone solution, we observed issuesof solvent penetrating the silicone tubing, just as it did when usingcarvone as solvent. However, the approaches found when working with thecarvone solutions work again in this case. Teflon tubing can be used ifflexibility is not required. For tubing attached to a moving print head,flexibility is important and therefore the alternate solution of sealingthe tubing with silicone grease (possible with a protective outer layerof tubing) is being evaluated.

Example 11

Preparation of 3D PEEK Products by Combination of Epoxy-PEEK in Fenchonewith PEEK Powder:

PEEK powder was deposited on a base, then fenchone solution ofepoxy-PEEK and photoinitiator was added, and the layer was exposed tothe UV light source for about 1 minute. The process was repeated tocreate a 2-layer specimen. We found that the UV curing providedadditional stability to the specimen. The resulting 3D PEEK product isshow in FIG. 7.

While the invention has been particularly shown and described withreference to a preferred embodiment and various alternate embodiments,it will be understood by persons skilled in the relevant art thatvarious changes in form and details can be made therein withoutdeparting from the spirit and scope of the invention. All printedpatents and publications referred to in this application are herebyincorporated herein in their entirety by this reference.

We claim:
 1. A method of manufacturing a three-dimensional article, themethod comprising: depositing a high-performance polymer (HPP)composition comprising: a homogenous mixture of a first HPP dissolved ina solvent; and a second HPP that is insoluble in the solvent; exposingthe HPP composition to a stimulus to form a polymer layer of thethree-dimensional article; and repeating the steps (a)-(b) to formremainder of the three-dimensional article; wherein the solventcomprises spearmint oil, α-terpinene, limonene, α-pinene, fenchone, orcombinations thereof.
 2. The method of claim 1, wherein the first HPPcomprises a polyketone.
 3. The method of claim 2, wherein the polyketonecomprises polyetheretherketone (PEEK), polyaryletherketone (PAEK),polyetherketone (PEK), polyetherketoneketone (PEKK)polyetheretheretherketone (PEEEK), polyetheretherketoneketone (PEEKK),polyetherketoneetheretherketone (PEKEKK), or polyetherketoneketoneketone(PEKKK).
 4. The method of claim 1, wherein the second HPP comprisespolyimides, polyketones, reduced forms of polyketones, orpolyethersulfones, and wherein the second HPP is not soluble in thesolvent.
 5. The method of claim 1, wherein the stimulus comprises heat,light, oxidation, reduction, acid catalysis, base catalysis, transitionmetal catalysis, or combination thereof.
 6. The method of claim 1,further comprising the step of curing wherein curing is done by chemicalcuring or thermal curing.
 7. A method for manufacturing athree-dimensional article, the method comprising: depositing a powder offirst HPP on a build plate to form a powder bed; printing a solutioncomprising a homogeneous mixture of a second HPP dissolved in a solventat selected locations on the powder bed; exposing the printed solutionto a stimulus to form a polymer layer of the three-dimensional article;and repeating steps (a)-(c) to manufacture remainder of thethree-dimensional article.
 8. The method of claim 7, wherein the firstHPP comprises polyimides, polyketones, reduced forms of polyketones, orpolyethersulfones, and wherein the first HPP is not soluble in thesolvent.
 9. The method of claim 7, wherein the second HPP comprises apolyketone.
 10. The method of claim 9, wherein the polyketone comprisespolyetheretherketone (PEEK), polyaryletherketone (PAEK), polyetherketone(PEK), polyetherketoneketone (PEKK) polyetheretheretherketone (PEEEK),polyetheretherketoneketone (PEEKK), polyetherketoneetheretherketone(PEKEKK), or polyetherketoneketoneketone (PEKKK).
 11. The method ofclaim 7, wherein the solvent has a low vapor pressure and is food-safe.12. The method of claim 11, wherein the solvent comprises spearmint oil,α-terpinene, limonene, α-pinene, fenchone, or combinations thereof. 13.The method of claim 7, wherein the stimulus comprises heat, light,oxidation, reduction, acid catalysis, base catalysis, transition metalcatalysis, or combination thereof.
 14. The method of claim 7, furthercomprising the step of curing wherein curing is done by chemical curingor thermal curing.
 15. A three-dimensional article made by the processof: depositing a high-performance polymer (HPP) composition comprising:a homogeneous mixture of a first HPP dissolved in a solvent; and asecond HPP that is insoluble in the solvent; exposing the HPPcomposition to a stimulus to form a polymer layer of thethree-dimensional article; repeating the steps (a)-(b) to form remainderof the three-dimensional article; and curing the article for less thanabout 1 minute; wherein the solvent comprises spearmint oil,α-terpinene, limonene, α-pinene, fenchone, or combinations thereof. 16.The method of claim 15, wherein the first HPP comprises a polyketone,wherein the polyketone comprises polyetheretherketone (PEEK),polyaryletherketone (PAEK), polyetherketone (PEK), polyetherketoneketone(PEKK) polyetheretheretherketone (PEEEK), polyetheretherketoneketone(PEEKK), polyetherketoneetheretherketone (PEKEKK), orpolyetherketoneketoneketone (PEKKK), wherein the second HPP comprisespolyimides, polyketones, reduced forms of polyketones, orpolyethersulfones, and wherein the second HPP is not soluble in thesolvent.
 17. The method of claim 15, wherein the stimulus comprisesheat, light, oxidation, reduction, acid catalysis, base catalysis,transition metal catalysis, or combination thereof.